There are currently over 500,000 slot machines in operation that together generate more than $15 billion in annual revenue for United States casinos. Most casinos generate more than half of their gaming revenues from slot machines and some individual casinos offer three or four thousand slot machines at a single location. In fact, two different casinos in Connecticut each provide over six thousand gaming devices for players.
Many players grow impatient and frustrated waiting for a slot machine outcome to resolve once they have pressed the “spin” button or made a handle pull. Further, casinos typically expect to earn an average amount of money, called the gaming device's “hold,” on a given number of spins. Therefore, the higher the rate at which spins are made, the more money a casino earns.